The ets oncongene superfamily codes for a family of transcriptional factors of which some are involved in leukemias, lymphomas and sarcomas. Previously, we have identified and characterized a new member of this oncogene family elk-1. Recently, we have shown that elk-1 is a transcriptional activator which regulates c-fos oncogene activity. We plan to study the mechanism of activation of fos by elk-1 proteins, identify the natural targets and study the role in cell growth, differentiation, signal transduction and cancer.